1. Field of the Invention
The present invention relates to a dispenser for a liquid crystal display panel and, more particularly, to a dispenser for a large scale liquid crystal display panel.
2. Discussion of the Related Art
In general, a liquid crystal display device is a display device where data signals according to picture information are individually supplied to liquid crystal cells arranged in a matrix form. Light transmittance of the liquid crystal cells is controlled in accordance with the data signals to display a desired picture. The liquid crystal display device includes a liquid crystal display panel where the liquid crystal cells are arranged in a matrix form, and a driver integrated circuit (IC) for driving the liquid crystal cells. The liquid crystal display panel includes a color filter substrate and a thin film transistor array substrate attached to each other. The liquid crystal display panel further includes a liquid crystal layer between the color filter substrate and the thin film transistor array substrate.
Data lines and gate lines are formed on the thin film transistor array substrate of the liquid crystal display panel and cross each other at right angles so as to define liquid crystal cells. The data lines transmit a data signal supplied from the data driver integrated circuit to the liquid crystal cells. The gate lines transmit a scan signal supplied from the gate driver integrated circuit to the liquid crystal cells. At an end portion of each of the data lines and the gate lines, a data pad and a gate pad are respectively provided in which data signals and scan signals are respectively applied from the data driver integrated circuit and the gate driver integrated circuit. The gate driver integrated circuit sequentially supplies a scan signal to the gate lines so that the liquid crystal cells arranged in the matrix form can be sequentially selected line by line while a data signal is supplied to the selected line of the liquid crystal cells from the data driver integrated circuit.
A common electrode and a pixel electrode are respectively formed on the inner side of the color filter substrate and the thin film transistor array substrate for applying an electric field to the liquid crystal layer of a liquid crystal cell. More particularly, a pixel electrode is respectively formed in each liquid crystal cell on the thin film transistor array substrate, while the common electrode is integrally formed across the entire surface of the color filter substrate. Therefore, by controlling a voltage applied to the pixel electrode while a voltage is applied to the common electrode, light transmittance of the liquid crystal cells can be individually controlled. To control the voltage applied to the pixel electrode by liquid crystal cells, a thin film transistor is formed in each liquid crystal cell and used as a switching device.
FIG. 1 is a plane view of the unit liquid crystal display panel formed by a thin film transistor array substrate and a color filter substrate according to the related art. As shown in FIG. 1, the liquid crystal display panel 100 includes an image display part 113 where the liquid crystal cells are arranged in a matrix form, a gate pad part 114 connected to the gate lines of the image display part 113, and a data pad part 115 connected to the data lines of the image display part 113. The gate pad part 114 and the data pad part 115 are formed along an edge region of the thin film transistor array substrate 101, which does not overlap with the color filter substrate 102. The gate pad part 114 supplies a scan signal from a gate driver integrated circuit (not shown) to the gate lines of the image display part 113, and the data pad part 115 supplies image information from a data driver integrated circuit (not shown) to the data lines of the image display part 113.
Data lines to which image information is applied and gate lines to which a scan signal is applied are provided on the thin film transistor array substrate 101. The data lines and the gate lines cross each other. Additionally, a thin film transistor for switching the liquid crystal cells is provided at each crossing of the data lines and the gate lines. A pixel electrode for driving the liquid crystal cells is connected to the thin film transistor and provided on the thin film transistor array substrate 101. A passivation film for protecting the pixel electrode and the thin film transistor is formed at the entire surface of the thin film transistor array substrate 101.
Color filters are provided on the color filter substrate 102 for each cell region. The color filters are separated by a black matrix. A common transparent electrode is also provided on the color filter substrate 102.
A cell gap is formed by a spacer between the thin film transistor array substrate 101 and the color filter substrate 102. A seal pattern 116 is formed along an outer edge of the image display part 113. The thin film transistor array substrate 101 and the color filter substrate 102 are attached by the seal pattern 116 to thereby form a unit liquid crystal display panel.
In fabricating the unit liquid crystal display panel, a method for simultaneously forming unit liquid crystal display panels on a large-scale mother substrate is generally used. Thus, a process is required for separating the unit liquid crystal display panels from the large-scale mother substrate. For example, a cutting process can be used on the mother substrate to separate the plurality of unit liquid crystal display panels formed thereon.
The seal pattern 116, as discussed above, has an opening. After the unit liquid crystal display panel is separated from the large-scale mother substrate, liquid crystal is injected through a liquid crystal injection opening to form a liquid crystal layer at the cell-gap, which separates the thin film transistor array substrate 101 and the color filter substrate 102. Then, the liquid crystal injection opening is sealed.
As mentioned above, the following steps are required to fabricate the unit liquid crystal display panel: the thin film transistor array substrate 101 and the color filter substrate 102 are separately fabricated on the first and second mother substrates, the first and second mother substrates are attached in such a manner that a uniform cell-gap is maintained therebetween, the attached first and second mother substrates are cut into unit panels, and then liquid crystal is injected to the cell-gap between the thin film transistor array substrate 101 and the color filter substrate 102. In particular, the process of forming the seal pattern 116 along an outer edge of the image display part 113 is required to attach the thin film transistor array substrate 101 and the color filter substrate 102. The related art process of forming a seal pattern will now be described.
FIGS. 2A and 2B illustrate a screen printing method to form a seal pattern. As shown in FIGS. 2A and 2B, there is provided a screen mask 206 patterned so that plural of seal pattern forming regions are selectively exposed. A rubber squeegee 208 is used to selectively supply a sealant 203 to the substrate 200 through the screen mask 206 so as to simultaneously form a plurality of seal patterns 216A-216F. The plurality of seal patterns 216A˜216F formed on the substrate 200 create a gap in which liquid crystal layer is later injected and prevent leakage of the liquid crystal. Thus, the plurality of seal patterns 216A˜216F are formed along each outer edge of the image display parts 213A˜213F of the substrate 200 and liquid crystal injection openings 204A˜204F are respectively formed for each of the seal patterns 216A˜216F.
The screen printing method includes: applying the sealant 203 on the screen mask 206 with the seal pattern forming regions patterned thereon, forming the plurality of seal patterns 216A˜216F on the substrate 200 through printing with the rubber squeegee 208; and evaporating a solvent contained in the seal patterns 216A˜216F and leveling them. The screen printing method is widely used because it is an easy process. However, the screen printing method is disadvantageous in that sealant 203 is wasted because a lot of sealant is discarded after the squeegee 208 is drawn across the screen mask to form the plurality of seal patterns 216A˜216F. In addition, the screen printing method has a problem in that rubbing of an orientation film (not shown) formed on the substrate 200 can incur defects when the screen mask 206 and the substrate 200 come into contact with each other. These defects will degrade picture quality of the liquid crystal display device.
To overcome the shortcomings of the screen printing method, a seal dispensing method has been proposed. FIG. 3 is an exemplary view of a related art dispensing method for forming a seal pattern. As shown in FIG. 3, while a table 310 with the substrate 300 loaded thereon is moved in forward/backward and left/right directions, a plurality of seal patterns 316A˜316F are formed along each outer edge of image display parts 313A˜313F on the substrate 300 by applying a predetermined pressure to syringes 301A˜301C filled with a sealant. The seal patterns 316A˜316F are sequentially formed for each line of the image display parts 313A˜313F in a line by line fashion.
In the seal dispensing method, since the sealant is selectively supplied to the region where the seal patterns 316A˜316F are to be formed, sealant waste is prevented. In addition, the syringes 301A˜301C do not contact the orientation film (not shown) of the image display part 313 of the substrate 300 so that the rubbed orientation film will not be damaged. Thus, picture quality of the liquid crystal display device will be maintained.
As more image display parts 313A˜313F are formed on the substrate 300, the more the fabrication yield and productivity improve. In order to form as many image display parts 313A˜313F as possible on one substrate 300, the size of the substrate 300 is increased. However, the related art, in which the syringes 301A˜301C are fixed while the table 310 with the substrate 300 loaded thereon is horizontally moved in forward/backward and left/right directions to form the seal patterns 316A˜316F, has the following problems. First, as the liquid crystal display panel is enlarged, the area of the substrate 300 for fabrication of the large-scale liquid crystal display panel increases accordingly. In order to form the seal patterns 316A˜316F on a large-scale substrate 300, the minimum distance that the table 310 needs to move is double the length of the shortest side of the substrate 300. Accordingly, if the dimensions of a substrate 300 are doubled, the size of the area that the table 310 needs to move about is increased by at least four times. Such an increase in the area for dispensing degrades the space use efficiency of a clean room. Second, because such a large mass of table 310 with the large-scale substrate 300 loaded thereon has to be moved in long forward/backward and left/right movements, more time is required to move the table 310 to accurately form the seal patterns 316A˜316F, which degrades productivity.